Explosion proof electrical connector operable upon engagement of plug and receptaclehalves



Feb. 15, 1966 H. P. PAPwoRTH 3,235,682

EXPLOSION PROOF ELECTRICAL CONNECTOR OPERABLE UPON ENGAGEMENT 0F PLUGAND RECEPTACLE HALVES Filed Feb. 24. 1964 5 Sheets-Sheet l Feb. 15, 1966H. P. PAPWORTH 3,235,682

EXPLOSION PROOF ELECTRICAL CONNECTOR OPERABLE UPON ENGAGEMENT OF PLUGAND RECEPTACLE HALVES Filed Feb. 24, 1964 3 Sheets-Sheet 2 INVENTOR.HUGH P. PA PWORTH ATTORNEY.

Feb. 15, 1966 H. P. PAPwoRTH 3,235,682

EXPLOSION PROOF ELECTRICAL CONNECTOR OPERBLE UPON ENGAGEMENT OF PLUG ANDREGEPTACLE HALVES Filed Feb. 24, 1964 3 Sheets-Sheet 3 FIG. IO

INVENTOR. HUGH P. PAPWORT H ATTORNEY.

United States Patent O 3,235,682 EXPLOSIGN PROOF ELECTRICAL CGNNECTOROPERABLE UPON ENGAGEMENT F PLUG AND RECEPTACLE HALVES Hugh P. Papworth,Syracuse, N.Y., assigner to Crouse- Hinds Company, Syracuse, N.Y., acorporation of New York Filed Feb. 24, 1964, Ser. No. 346,749 3 Claims.(Cl. 20D-51.09)

This invention relates to and has as a general object a new and improvedexplosion proof electrical connector.

In hazardous locations which may be dened as locations in which thesurrounding atmospheres contain sufiicient quantities of flammablevapors, gases, or highly combustible dusts, to create explosivemixtures, it is necessary to use explosion proof electrical devices.However, due to the fact that the different vapors, gases and dusts havedifferent ignition temperatures, and when exploded produce differentpressures, the various types of atmospheres containing different type ofexplosive mixtures have been categorized by fire underwriter groups, orthe like, and electrical devices must be approved for use in the variousclasses before they can be installed in locations which contain thevarious mixtures of explosive gases.

The National Electrical Code categorizes the locations in which thehazards are due to flammable vapors or gases, as Class I, and those inwhich the hazards are due to combustible dusts as Class II. Thisclassication is further broken down according t0 groups as follows:

containing ethyl ether This invention is directed to an electricalconnector designed for use in Class I, Group B, and as will be seen fromthe above-set-forth classification, which is generally arranged in orderof most hazardous gases, first, and least hazardous mixtures last, GroupB gases rank second in hazard.

Accordingly, it is a more specific object of the invention to provide anew and improved explosion proof electrical connector of the plug andreceptacle type which may be safely employed in atmospheres containingexplosive mixtures of Class I, Group B, gases.

As is well known in the art, one of the leading methods of manufacturingexplosion proof equipment is to design the equipment so that anyexplosion created by arcs, static sparks, or any other type ofelectrical ignition is confined within an enclosure which is ofsuiiicient physical strength to withstand the momentary high pressurecreated by the explosion and wherein the leakage paths from theenclosure are of suflicient length and closeness to lower thetemperature of the gases to beneath the ignition point of thesurrounding hazardous gas mixture. Such paths are termed flame-quenchingpaths in the art, and have taken the form of threaded paths wherein theiiame or hot gas must follow a long tortuous route from the enclosedarea or explosion proof 3,235,632 Patented Feb. 15, 1966 chamber to theoutside atmosphere, or wherein the path is smooth, but the tolerancesare held sutiiciently close, and the length of the path is suiiicientlylong to provide the necessary llame-quenching and cooling eifect.

In large current conducting devices, it has heretofore been necessary touse heavy cast iron housings, to enclose electrical equipment, so as tocontain any explosion created by an electrical ignition of the hazardousmixture within the enclosure by an arc or static spark. For

example, where circuit breaking devices were desired in Class Blocations, it has been necessary to utilize large heavy weightenclosures for the circuit breaker, and a plug mechanically interlockswith a receptacle carried by the breaker so that the plug cannot bewithdrawn from the receptacle until the circuit breaker is operated tobreak the circuit. In such an arrangement any explosion created by theignition of gases in the circuit breaker enclosure caused by the arcgenerated by the operation of the breaker is contained within thebreaker housing or enclosure. Such combination circuit breakers andinterlocked plug and receptacles are not only of great size and weight,they are in addition very expensive.

Accordingly, it is a more specific object of the invention to provide acircuit breaking electrical connector which is relatively compact, andexplosion proof, yet at the same time is reliable and simple inoperation and economical to manufacture.

It is further desirable that circuit breaking electrical connectors ofthis general type .be arranged so that the receptacle contacts areelectrically dead when the plug is disengaged from the receptacle. Thisprevents shock hazard and further eliminates the possibility of thereceptacle contacts being accidentally engaged by a metallic substanceso as to create an electric arc.

Accordingly, it is a further object of the invention to provide a newand improved dead front explosion proot electrical receptacle.

All known prior devices of this general type, both explosion proof anddead front have operated in one of two general manners. The first typeof such connectors is that wherein the plug is inserted in thereceptacle to cause an electrical engagement of the plug and receptaclecontacts and the plug is then rotated, which rotation serves to connectpower to the receptacle contacts, and in turn to the plug contacts. Suchdevices are difficult and expensive to make, and further it is extremelydifficult to construct the switching chamber in a manner so as to meetthe standards of fire underwriters and the like, for Group B gases. Thesecond general type of such prior'art connectors are those wherein theplug carries a switch operator so that upon insertion of the plug intothe receptacle, whereby the plug and receptacle contacts are engaged,the operator carried by the plug engages cooperable operating means inthe receptacle, so that upon rotation of the plug operator, theswitching is effected to connect the power to the receptacle contacts,and again, in turn to the plug contacts. This type of device becomesvery cumbersome and expensive to manufacture because of the independentoperator and co-operable operating means carried by the plug andreceptacle, respectively.

Accordingly, it is a more specific object of this invention to provide aunique and novel circuit breaking electrical connector of the explosionproof dead front variety, wherein the receptacle contacts are normallydisengaged from the power contacts and upon axial insertion of the pluginto the receptacle in a straight non-rotating fashion, the receptacleand plug contacts are rst engaged, and upon continued axial insertion ofthe plug power contacts are connected to the receptacle contacts tocomplete the circuit to the plug contacts (the order being reversed uponwithdrawal of the plug), and wherein the connection between the powercontacts and the receptacle contacts takes place in an explosion proofchamber, into which the inner ends of the receptacle contacts extend.

The invention consists in the novel features and constructions and themethod hereinafter set forth and claimed.

lIn describing the invention, reference is had to the accompanyingdrawings in which like characters designate corresponding parts in allthe views.

In the drawings:

FIGURE 1 is an elevational cross-sectional view of the preferredembodiment of the plug and receptacle of the invention wherein the plugis shown in axial alignment with, but separated from the receptacle.

FIGURE 2 is a sectional view similar to FIGURE 1, but wherein the plughas lbeen shown as fully inserted into the receptacle.

FIGURE 3 is a View taken looking in the direction of the arrows of line3 3 of FIGURE l.

FIGURE 4 is a view taken looking in the direction of the arrows of line4 4 of FIGURE l.

FIGURE 5 is a View taken looking in the direction of the arrows vof line5 5 of FIGURE 1.

FIGURE 46 is an elevational view with parts broken away and parts insection of a portion of the receptacle.

FIGURE 7 is a View taken looking in the direction of arrows of line 7 7of FIGURE 6.

FIGURE 8 is an end view looking to the right `of FIGURE 6.

FIGURE 9 is an end view looking to the left of FIG- URE 6 with portionsbroken away and portions in section.

FIGURE 10 is a view of the laid-out surface of an ele-ment of theinvention.

FIGURE 11 is an elevational view of an explosion housing for thereceptacle of the invention, shown mounted in an electrical conduitsystem.

Referring to FIGURE l, the plug housing or shell, is generally indicatedat 10, and is made up of a forward portion 12 which is open at itsrearward end, and internally threaded, as at 14. The forward end of theportion 12 is reduced in diameter to form a shoulder 16 and extendsaxially forward from the shoulder 16 to form the plug skirt 18. Receivedin the portion 12 and abutting against an internal shoulder 19 is adielectric insert 2t), in which are mounted a plurality of pin typeelectrical contacts 22. The contacts 22 are of the conventional varietyhaving an annular groove to receive an O-ring 23, and are provided withan axial slot 24 at their forward edge and an electrical conductorreceiving socket 26 at their rearward end.

While the number of the contacts 22 has been shown to be S, it will beunderstood that any suitable number of contacts may be carried by theinsert 20. Carried in a central rectangular slot 30 formed in thedielectric insert is a helical actuator 32 which extends through areduced aperture communicating with the slot Si) and formed in theforward end of insert 2t). The actuator terminates at its forward endwithin the plug skirt 18, and is formed with a portion 34 located in aplane 90 out of the phase with the plane of the portion 32, whereby thehelical surfaces 36 and 38 serve to join the portion 34 to the portion32. The portion 32 extends beyond the inner end of the insert 20, as dothe sockets 26 of the contacts 22. Power conductors, generally indicatedat 34, are introduced into the sockets 26 and are mechanically fixedtherein by any suitable means, as for example by set screws 33 (see alsoFIGURE 3). The inner end of the helix actuator 32 is apertured toreceive a pin 38 to maintain the actuator in the dielectric piece 20. Asecond dielectric piece 40 provided wth a central cored-out portion 42,and through apertures 44 for the contact sockets 26, abuts a gasket 45and the iirst dielectric insert 2t) and is maintained in this positionby a rearward shell portion 46, which is externally threaded to matewith the threads 14 in the shell portion 12, and is fixed in threadedengagement by set screw 47. The shell portion 46 may, if desired, beprovided with a threaded aperture closed by a plug, so that a sealingcompound may be introduced into the plug, rearwardly' of the insert 40to seal the power conductors 34 in the plug 10.

Referring to FIGURE 3, it will be seen that the plug contacts 22 areasymmetrically positioned in the insert 2B in a preselected arrangementto aid in polarizing the plug and receptacle. Finally, it will be seenin FIGURE l, an internally threaded coupling nut 50 is carried on theportion 12 of the plug 10 between the shoulder 16 and tiange S2 formedon the portion 46 for a purpose to be hereinafter described.

Referring again to FIGURES 1 and 2, the receptacle is generallydesignated by the reference numeral 6d, and is received in the forwardportion 62 of a housing (to be shown in detail hereinafter) open at itsrearward end to permit introduction of the power conductors 68. Theouter end of portion 62 is threaded complementally to the threads on theplug coupling nut 50 to permit the nut to be attached thereto.

A cylindrical dielectric insert is received in the portion 62 of thereceptacle housing by means of the annular threaded ring 82 carried bythe insert 80, and an internally complementally threaded portion 84 inthe housing 62.

The forward portion of the insert 80, which may be termed a silo isformed of a plurality of cylindrically cored-out portions 86, in whichare received a plurality of receptacle contacts of the socket type, toreceive the plug contacts 22. Again, thereceptacle contacts 90 are shownto be 5 in number, and are positioned complementally to the positioningof the plug contacts, but it will be understood that any suitable numberof receptacle contacts can be carried by the receptacle, and they may bepositioned in any suitable arrangement.

One of the receptacle contacts, indicated by the reference numeral 92,extends rearwardly through the insert 80 to the rear face 94 thereof,and is drilled at its inner end to receive a pin portion 96 formed on aground contact 9S, which is provided at its rearward end with a socket109 to receive a ground lead, or conductor 102. The ground conductor 102is iixedly mounted in the socket by the set screw 104. As best seen inFIG- URE 1, the dielectric insert Sti is formed with the annular skirtportion 196, which is interiorly cored, so as to form an explosion proofswitching chamber M98. This chamber is closed by a second dielectricpiece 110, which is aflixed to the skirt 196 by means of threadedfasteners 112, which pass through insert 110, and are received in tappedholes formed with axially extending ribs or thickened portions in thering 106 (see FIGURE 5). A plurality of shouldered bridging contacts 114are carried by the dielectric piece 110 by any suitable means, and thebridging contacts are connected to the power conductors 68 by the setscrews 104. As best seen in FIGURES 1, 2 and 5, the insert 110 is formedwith a raised portion 111 on its rear surface in which the apertures forthe hot contacts 114 are formed, and a raised portion 115, in which theaperture for the ground contact 98 is formed.

Connected to the interior end of the bridging contacts 114, each ofwhich are formed with a socket aperture 116, are the rearward pin typeends 113l of power connecting contacts formed at their forward or innerend with butt type contact faces 122. The power connecting contacts 120are moved axially by means to be hereinafter described, to move thecontact faces 122 into abutting engagement with contact faces 124 formedon the rearward inner end of the receptacle contacts 90. As best seen inFIGURE 2, the power connecting contacts 120 have been moved axially fromthe position shown in FIG- URE 1 to engage their contact faces 122 withthe contact faces 124 of the receptacle contacts 9i). As will also beseen in FIGURE 2, the plug contacts 22 are engaged in the aperture orsocket 91 formed in the receptacle contacts, all

whereby the power is connected from vthe leads 68 through the connectorto the leads 34 carried by the plug.

The insertion and axially inward movement of the plug into thereceptacle 60 operates the means which effect the axial motion of thepower connecting contacts 120. Referring to FIGURES 3 to 9, inclusive,this means will next be described. As best seen in FIGURES 1 and 2, thedielectric insert 80 is provided at its center with an aperture 130which extends through the insert 80 into the inner end thereof, where itenters the chamber 108 formed by the attachment of the rear insert piece110 to the dielectric insert 80. The central aperture 130 is threaded asat 132, intermediate its ends to receive a complementally threadedportion`134 of a cylinder 136.

The forward portion of the cylinder 136 is provided with a centralcylindrical aperture 138 for a purpose to be hereinafter described, andthe rearward portion of the cylinder terminates in a stub shaft 140 toreduced diameter. As best seen in FIGURES 1 and 2, the rearward end ofthe stub shaft 140 is received in an aperture 142 formed in the rearwarddielectric piece 110' in order t0 provide a pilot bearing for therotation of cylinder 136. The stub shaft 140 is provided at its innerend with a through aperture 143, and a cam actuator 144 formed with acentral aperture 146 corresponding to the diameter of the stub shaft 140is received on the shaft 140 and affixed thereto by means of a roll pin148, which passes through a pair of radial apertures 150 formed on theinner end of the actuator 144 and the through aperture 142 formed in thestub shaft 140, all whereby the cam actuator 144 will rotate with theshaft 140 upon rotation of the cylinder 136.

As best seen in FIGURE 10, which is a layout of the surface of the camactuator 144, the actuator is provided with three cam tracks 152, 154,and 156, located 120 degrees apart. Cam track 154, which isrepresentative of all cam tracks, is made up of an axially extendingportion 158 which is provided at its upper end portion with a circulardepressed portion 160 forming a detent aperture for a purpose to behereinafter described. The remainder of the cam track 154, indicated at162, extends circumferentially and in spiral fashion along the surfaceof the actuator 144, and terminates at its inner end in a further detentdepression 164. The detents 160 and 164 are located 90 degrees apart,thus describing the rotational limit of the actuator 144, as will behereinafter understood. As best seen in FIGURE 6, the cam tracks 152,154 and 156 are formed by relieving the surface of the carn actuator144, so that the -bottom portion of the tracks is below the surface ofthe actuator 144, and the detents 160 and 164 are located below thesurface of the cam tracks.

Referring again to FIGURES l and 2, it will be seen that the powerconnecting contacts 120 are carried by a carrier plate 170, which iscomposed of a pair of identical formed pieces 172 and 174 to permitassembly of the contacts 128 to the plate 17 0. As best seen in FIGURE6, the connection of the contacts to the plate is effected by means of asnap ring 176 which is connected to the shank portion of the contact128, and the snap ring 176 is carried in the chamber 178 formed by thehollowed-out inner portions of the pieces 172 and 174 forming thecarrier plate. The butt contact portion 122 of contact 120 is enlargedso as to provide a shoulder and the outer face of the carrier plate 17@to yieldingly bias the contacts to the position shown in FIGURES 1 and6, wherein the ring 176 engages the underside of the carrier plate piece174. As will be obvious, this yieldable mounting of the power contacts120 is necessary to compensate for variations and irregularities in themanufacture and assembly of the receptacle so that each of the contacts126 will fully engage each of the contacts 98 through their contactfaces 122 and 124.

As best seen in FIGURE 9, the pieces 172 and 174 forming the carrierplate 170 are provided with three radially extending apertures, one ofwhich is shown in the broken away sections in FIGURE 9, and is indicatedby the reference numeral 184. Mounted in the apertures 184 are threedetent pins 186, which are yieldingly urged into the central aperture188 formed in the carrier plate 170 by means of compression springs 190carried in the apertures 184 between the rearward end of the pins 186and the bottom of the apertures 184. As will be understood, these detentpins engage and ride in the cam tracks 152, 154, and 156, formed in thesurface of the cam actuator 144. Accordingly, upon rotation of thecylinder 136, the cam actuator 144 will be rotated 90l degrees andthrough the means of the cam tracks 152, 154 and 156, and the detentpins 186, which are normally received in the detents will pass along thespiral leg 162 of the cam tracks, and into the detents 164. The carrierplate will be moved forwardly in the chamber 108 formed by thedielectric inserts 110- and 80, to effect connection of the powercontacts 120 with the receptacle contacts 90. Reverse rotation of thecylinder 136 will reverse the action and return the detent pin 186 tothe detents 160, thus separating the power and receptacle contacts.

The rotation of the cylinder which may also be termed an actuator 136,is effected -by the insertion of the plug in the receptacle. Referringto FIGURES 6, 7 and 8, the forward end of the cylindrical aperture 138formed in the cylinder 136 is closed by a guide piece 192. The guidepiece 192 is formed on its forward face with a rectangular aperture 194having a beveled entrance complemental in dimension, but oversize, tothe rectangular dimension of the forward portion 34 of the helicalactuator 32 carried by the plug 10. The guide piece 192 is pro-videdwith a pair of radial apertures 195 extending normally to the guideaperture 194, and the forward end of the cylinder 136 is provided with apair of radial apertures 198, to receive a pair of roll pins 260 tofixedly connect the guide piece 192 to the cylinder 136. The cylinder136 is provided with an annular channel 202, in which a gasket 204 isreceived, the gasket 284 engaging the aperture 138 formed in thedielectric insert 80.

. As will be understood, when the plug skirt 18 having an axiallyextending keyway 206 is properly orientated, and inserted into thereceptacle housing 60, so that the polarizing lug 208 enters the keyway206, the forward portion 34 of the helical actuator 32 will enter therectangular guide aperture 194 of the guide piece 192 carried by thecylinder 136. Continued inner movement of the plug 1t) into thereceptacle 60 will, due to the helical portions 36 and 38 on the helicalactuator, cause rotation of the cylinder 136, as the forward portion 34of the helical actuator is received in the aperture 138 formed in thecylinder 136. As will be understood, this will effect a 90 rotation ofthe cylinder 136, and in turn a 90 rotation of the actuator 144 carriedthereby, The rotation of the actuator 144 will, through the agency ofthe detent pins 186, carried by the carrier plate 170, effect a forwardmovement of the carrier plate 170, and the power contacts 120 carriedthereby.

For assembly purposes, the detent pins 186 pass along the axial portions158 of the cam tracks 152, 154 and 156, and when they reach the innerend thereof, they will snap into the detent apertures or depressions160. Accordingly, rotation of the actuator 144, as above set forth, willcause the pins 186 to move out of the detents 160 and along the spirallyextending portions 162 of the cam tracks until the detent pins 186 arereceived in the detent depressions 164 formed at the inner end of thecam tracks. At this point, the power contacts have moved from theposition shown in FIGURE 1 to the position shown in FIGURE 2, so thatthe contact faces 122 thereof are in engagement with the contact faces124 carried by the rearward ends of the receptacle contacts 90. As alsoseen in FIGURE 2, the plug 10 is at this point fully inserted in thereceptacle 60 with the plug contacts 22 in full engagement with thesockets 91 formed in the receptacle contacts 90, and the helicalactuator 32 has passed fully through the guide aperture 194 formed inthe guide piece 192, carried by the forward end of the cylinder 136. Aswill be obvious, withdrawal of the plug from the receptacle will effectthe reverse operation causing the power contacts 120 t-o first separatefrom the receptacle contacts 90, and thereafter the plug contacts 22will be Withdrawn from the sockets 91 formed in the receptacle contacts.

It will be therefore understood, that the plug contacts are inmechanical and electrical engagement with the receptacle contacts priorto the engagement of the power contacts, with the inner end of thereceptacle contacts, and the plug and receptacle contacts stay in suchengagement until the power contacts have been separated from the innerends of the receptacle contacts, and power has been thereby disconnectedfrom the plug contacts. The engagement of the contact faces 122 and 124takes place l within an arc retaining sleeve 212 carried by the innerend of the receptacle contact apertures formed in the dielectric piece80. These arc containing sleeves may be of any suitable material, andserve to aid in extinguishing the electrical arc caused by theseparation of the contact faces 122 and 124.

It will be understood and be apparent from the description thus far,that any and all electrical arcing will take place within the sleeves212 and the chamber 108. The receptacle contacts 90 are molded, orotherwise suitably imbedded in the dielectric piece 80, so as to preventthe forward leakage of any high temperature gases or ame from theinterior of the unit cau-sed by ignition of explosive gases in thechamber 108 during the contact separation operation. A flame tight pathis also provided by the engagement between the threads 134 on thecylinder 136, and the threads 132 formed in the aperture 130 of thedielectric piece 80, so that there is no ame path from the archingchamber 108 forwardly through the receptacle 60.

The rearward portion of the receptacle is mounted in an explosion proofconduit housing, so that any rearward flame or high temperature gastravel or path is prevented. The mounting of the rear portion of thereceptacle is best seen in FIGURE ll, wherein the empty receptacle shellportion 62 is shown as being one leg 220 of a Y-type conduit housing, orfitting 222. The other leg 224 of the iitting 222 is provided at itsopposite ends with threaded apertures to receive threaded conduitnipples 226 and 228. T-he nipple 228 is fixed in place in the leg 224 ofthe housing 222 by set screw 230, carried by a threaded aperture formedin ear 232 formed on the leg 224, adjacent the threaded aperturethere-of,

In actual installation, a sealing fitting is placed on either the top orbottom of the installation, one of which is indicated at 234. Finally,the fitting 222 is provided with a wire pulling aperture 236, which isclosed by a threaded cover 238 to facilitate the connection of the powerleads to the receptacle.

It will be understood therefore, from the description of theinstallation of fitting 222, that the receptacle is connected to a powersupply in an explosion proof manner, so that any rearward escape of hotgases, or flame caused by the ignition of explosive gases in the arcingchamber 108 of the receptacle are continued within the fitting 222, in amanner which will permit their escape to the surrounding atrnosphereonly after they have sutiiciently cooled to prevent an ignition of thesurrounding atmosphere. The shell 62 of leg 220 is provided with one ormore grounding straps 210 mounted in axial recesses 242 formed in theinterior wall of shell 62 and adapted to engage plug skirt 18 to groundthe plug housing in the conventional manner.

It is to be understood that, while the receptacle 60 has been shown asbeing formed in the leg 220 of a conduit fitting, this showing is by wayof illustration only, to indicate a suitable arrangement for use inhydrogen laden atmospheres, and in other less hazardous atmospheres thereceptacle 60 may be differently formed, and in fact may be formed in amanner whereby it is connected to a cord, so as to form with the plug 10a cord connector unit.

Also it is to be understood that the detailed showing of the manner ofconstruction of the plug and receptacle are illustrative only, anddetails thereof may be varied in any suitable manner without departingfrom the essence of the invention, and accordingly, the scope of theinvention is to be limited only by the appended claims.

l What is claimed is:

1. An electrical connector comprising a plug half and a receptacle half,said halves adapted to be telescopically engaged, plug current carryingcontacts carried by said plug half, and receptacle current carryingcontacts carried by said receptacle half, said plug and receptaclecontacts being complementally positioned in said halves so as to axiallyengage upon axial engagement of said halves, said Vreceptacle beingformed with an explosion proof chamber, said receptacle current carryingcontacts extending into Vsaid chamber, a power supply contact mounted insaid receptacle in axial alignment with each of said current carryingreceptacle contacts and being axially spaced therefrom, said powersupply contacts being connected to a power supply, a power connectingcon tact mounted in said explosion proof chamber in axial alignment witheach of said receptacle contacts, like ends of said power connectingcontacts having axially slidable engagement with said power supplycontacts, the opposite ends of said power connecting contacts beingnormally spaced from said current carrying receptacle contacts, contactactuating means mounted in said explosion proof chamber, means carriedby said plug cooperable with said contact actuating means uponengagement of said plug and receptacle halves to effect axial movementof said power connecting contacts into engagement with said receptaclecurrent carrying contacts to connect the same to said power supplycontacts.

2. An electrical connector comprising a plug half and a receptacle half,said halves adapted to be telescopically engaged, plug current carryingcontacts carried by said plug half, and receptacle current carryingcontacts carried by said receptacle half, said plug and receptaclecontacts being complementally positioned in said halves so as to axiallyengage upon axial engagement of said halves, said receptacle beingformed with an explosion proof chamber, said receptacle current carryingcontacts extending into said chamber, a power supply Contact mounted insaid receptacle in axial alignment with each of said -current carryingreceptacle contacts and being axially spaced therefrom, an annularmember mounted in said explosion proof chamber, a power connectingcontact carried by said annular member and axially aligned with each ofsaid current carrying receptacle contacts, like ends of said powerconnecting contacts having axially slidable engagement with said powersupply contacts, the opposite ends of said power connecting contactsbeing normally spaced from said receptacle current carrying contacts, anactuator mounted in the receptacle and being operatively connected tosaid annular member, said actuator and said plug half having co-actingmeans operable upon axial engagement of said halves to effect movementof s-aid annular member to move said power connecting contacts intoengagement with said current carrying receptacle contacts, and upondisengagement of said halves to move said power connecting contactsaxially out of engagernent with said current carrying receptaclecontacts.

3. An electrical connector comprising a plug half and a receptacle half,said halves adapted to be telescopically engaged, plug current carryingcont-acts carried by said plu-g half, and receptacle current carryingcontacts carried by said receptacle half, said plug and receptaclecontacts being complementally positioned in said halves so as to axiallyengage upon axial engagement of said halves, said receptacle beingformed with an explosion proof chamber, said receptacle current carryingcontacts extending into said chamber, a power supply contact mounted insaid receptacle in axial alignment with each of said current carryingreceptacle contacts and being -axially spaced therefrom, an actuatormounted in the receptacle for rotation yabout the axis thereof andhaving a portion extending into said explosion proof chamber, an annularmember in said chamber encircling said actuator, a power connectingcontact carried by said annular member and -axially aligned with each ofsaid current carrying receptacle contacts, like ends of said powerconnecting contacts having axially slidable engagement with said powersupply contacts, the opposite ends of said power connecting contactsbeing normally spaced from said current carrying receptacle cont-acts,said actuator and plug half having co-acting means operable upon axialengagement of said half to eiect rotation of said actuator in a rstdirection and upon disengagement of said half to effect rotation of saidactuator in the opposite direction, said actuator and annular memberhaving co-acting cam means operable upon rotation of said actuator insaid first direction to move said power connecting contacts axially intoengagement with said receptacle current carrying contacts, and uponrotation of said actuator in said opposite direction to move said powerconnecting contacts axially lout of engagement with said receptaclecurrent carrying contacts.

References Cited by the Examiner UNITED STATES PATENTS 1,686,347 10/1928 Scheuerman 20G-51.09 2,951,138 8/1960 Petrino 200-153 3,078,435 2/1963 Berry 339-111 KATHLEEN H. CLAFFY, Primary Examiner.

BERNARD A, GILHEANY, Examiner.

1. AN ELECTRICAL CONNECTOR COMPRISING A PLUG HALF AND A RECEPTACLE HALF,SAID HALVES ADAPTED TO BE TELESCOPICALLY ENGAGED, PLUG CURRENT CARRYINGCONTACTS CARRIED BY SAID PLUG HALF, AND RECEPTACLE CURRENT CARRYINGCONTACTS CARRIED BY SAID RECEPTACLE HALF, SAID PLUG AND RECEPTACLECONTACTS BEING COMPLEMENTALLY POSITIONED IN SAID HALVES SO AS TO AXIALLYENGAGE UPON AXIAL ENGAGEMENT OF SAID HALVES, SAID RECEPTACLE BEINGFORMED WITH AN EXPLOSION PROOF CHAMBER, SAID RECEPTACLE CURRENT CARRYINGCONTACTS EXTENDING INTO SAID CHAMBER, A POWER SUPPLY CONTACT MOUNTED INSAID RECEPTACLE IN AXIAL ALIGNMENT WITH EACH OF SAID CURRENT CARRYINGRECEPTACLE CONTACTS AND BEING AXIALLY SPACED THEREFROM, SAID POWERSUPPLY CONTACTS BEING CONNECTED TO A POWER SUPPLY, A POWER CONNECTINGCONTACT MOUNTED IN SAID EXPLOSION PROOF CHAMBER IN AXIAL ALIGNMENT WITHEACH OF SAID RECEPTACLE CONTACTS, LIKE ENDS OF SAID POWER CONNECTINGCONTACTS HAVING AXIALLY SLIDABLE ENGAGEMENT WITH SAID POWER SUPPLYCONTACTS, THE OPPOSITE ENDS OF SAID POWER CONNECTING CONTACTS BEINGNORMALLY SPACED FROM SAID CURRENT CARRYING RECEPTACLE CONTACTS, CONTACTACTUATING MEANS MOUNTED IN SAID EXPLOSION PROOF CHAMBER, MEANS CARRIEDBY SAID PLUG COOPERABLE WITH SAID CONTACT ACTUATING MEANS UPONENGAGEMENT OF SAID PLUG AND RECEPTACLE HALVE TO EFFECT AXIAL MOVEMENT OFSAID POWER CONNECTING CONTACTS INTO ENGAGEMENT WITH SAID RECEPTACLECURRENT CARRYING CONTACTS TO CONNECT THE SAME TO SAID POWER SUPPLYCONTACTS.